ClassCastException #9

Hello there,

I tried using version 1.1.2. I installed java-oo on my Intellij IDEA and copy-pasted Example1 of yours. Now, the operators (*, +) are marked as wrong by the IDE (with the warning: Operator '*' cannot be applied to 'symjava.symbolic.Symbol', 'symjava.symbolic.Symbol'"). When I try to compile, there is the following error:

java: java.lang.ClassCastException: class com.sun.proxy.$Proxy25 cannot be cast to class com.sun.tools.javac.processing.JavacProcessingEnvironment (com.sun.proxy.$Proxy25 is in unnamed module of loader java.net.URLClassLoader @2ff4acd0; com.sun.tools.javac.processing.JavacProcessingEnvironment is in module jdk.compiler of loader 'app')

Do you have an idea what might have gone wrong here? I am using Intellij IDEA 2020.3.2 (Ultimate Edition) with Java 15.0.1.